docs: def refresh_lock(lock_file):
      """'Refresh' an existing lock.
  
      'Refresh' an existing lock by re-writing the file containing the
      owner's unique id, using a new (randomly generated) id, which is also
      returned.
  
      """
      unique_id = '%s_%s_%s' % (
          os.getpid(),
          ''.join([str(random.randint(0, 9)) for i in range(10)]), hostname)
      try:
          lock_write = open(lock_file, 'w')
          lock_write.write(unique_id + '\n')
          lock_write.close()
      except Exception:
          # In some strange case, this happen.  To prevent all tests
          # from failing, we release the lock, but as there is a
          # problem, we still keep the original exception.
          # This way, only 1 test would fail.
          while get_lock.n_lock > 0:
              release_lock()
          raise
      return unique_id